1. Field of Invention
The present invention relates to subsea shelters for abandoned wellheads and the like and more particularly to a system which may be installed underwater without the need for underwater assistance from divers or the like, the system allowing full installation from the surface, utilizing conventional oilfield tools and equipment.
The present invention teaches a new and unique system for lowering and centering the shelter over the wellhead, as well as a new system for the preparation of the installation site, including the removal of debris from the site and excavation of the ground surface area about the abandoned wellhead via a remote, fluid actuated excavation system.
The present invention, with the utilization of a somewhat pyramidally or frustoconically configured shelter structure, teaches a conduit system from the top of the structure to the base, terminating in a plurality of excavation jets about the periphery of the base area, providing a fluid stream of adjustable intensity (depending upon the excavation surface) for "trenching" the installation area, thereby allowing the base of the structure to sit below the over-all ground surface.
The present invention provides a new, innovative, and less expensive system for the installation of abandoned wellhead shelters and the like in an underwater environment.
2. Prior Art and General Background
While the prior art is replete with various designs for sheltering abandoned wellheads, valve stems, and the like, until now there has been no known system for installing these structures in a suitable manner without the necessity of a commercial diving team for preparing the installation site and supervising the installation and centering of the structure about the area to be sheltered.
The desirability in dispensing with the necessity of commercial divers in the present system is apparent when taking into account the extraordinary costs associated with retaining and utilizing a commercial dive team, and support team and platform. Plus, the utilization of divers requires additional time considerations, including an intolerance for less than optimal weather and/or sea conditions.
It is well known that the cost of supporting a typical commercial diver team and support in installing the typical abandoned wellhead shelter normally far exceeds the cost of providing the shelter itself. For example, the cost of a typical wellhead shelter may run $8,000.00-$10,000.00, while the dive team and support can easily run $10,000.00-$15,000.00 and higher, depending upon the job, depth and conditions.
Thus, not only could dispensing with the necessity of divers decrease the cost of providing abandoned wellhead shelters, also there is a time savings factor, with a major time and expense factor in the installation procedure being removed.
A list of prior patents which may be of interest is presented below:
______________________________________ Patent No. Patentee(s) Issue Date ______________________________________ 4,919,210 Shaefer April 24, 1990 4,452,312 Roblin June 5, 1984 4,323,118 Bergmann Apr. 6, 1982 3,543,846 Smith Dec. 1, 1970 3,516,489 Jergins June 23, 1970 3,063,500 Logan Nov. 13, 1962 1,721,805 Cormier July 23, 1929 ______________________________________
As may be discerned by a review of the above patents, the prior art does not teach a self-installable structural device or method for sheltering permanently or temporarily abandoned subsea wellheads, while being configured so as not to interfere with users of the seabed such as commercial fisherman and the like.
U.S. Pat. No. 3,063,500 issued 1962 and entitled "Underwater Christmas Tree Protector" teaches "an underwater housing or protector for protecting an underwater christmas tree".
This patent teaches a cylindrical shelter for underwater christmas trees for protecting the christmas tree from the corrosive effects of salt water. The shelter is in the form of a large diameter pipe driven into the sea floor, enveloping the christmas tree. In order to protect the christmas tree from corrosion, a protective oil fills the structure, thus providing a corrosion free environment for the christmas tree.
As may be further determined by a review of the patent, the structure is obviously distinguishable from the invention made the subject this application. The patent relates to a watertight, oil filled structure designed to envelope a christmas tree for corrosion prevention.
The structure as disclosed above is not suitable for the contemplated use as taught in the present invention. Further, the structure is not configured in such a manner as to protect the wellhead and commercial users of the sea bottom in accordance with the Federal Regulations; nor does the above invention teach an easily installed shelter, but rather a complicated, extensive scheme to prevent saltwater corrosion of underwater christmas trees.
Indeed, the configuration of the above structure invites the entanglement of trawls, nets, or the like which might pass over it. The main body of the structure is in the same cylindrical, vertical form as the naked wellhead, and thus provides little utility or opportunity for use under the federal guidelines discussed above. The elongated rods implemented in a horizontal sloping form above the shelter as disclosed in FIG. 4 would not prove effective in preventing nets, anchors, etc., from becoming entangled in the structure and would in fact invite entanglement.
U.S. Pat. No. 3,543,846 issued 1970 and entitled "Underwater Oil or Gas Facility" teaches a reinforced concrete underwater structure of a frustoconical configuration having the capability of serving as an underwater production, oil-gas separation facility, or storage facility.
The principal embodiment of the above patent teaches a rather large underwater structure, essentially serving as an underwater production platform. The exemplary embodiment appears to be the height of a 15 story building, and figures in the patent show personnel operating equipment therein.
Again, the present invention is obviously distinguishable from the above patent; the similarity of the general configuration of the two structures is the only pertinent trait. The patent does not teach an easily implemented, cost effective wellhead shelter and method of isolating the wellhead such that is does not pose a hinderance to navigation or commerce as disclosed in the present invention and is thus readily distinguishable.
Finally, U.S. Pat. No. 4,919,210 issued Apr. 24, 1990 to the present applicant entitled "Subsea Wellhead Protection System", teaches a system for the sheltering of submerged, permanently or temporarily abandoned wellheads or the like, utilizing a sloped structure configured to prevent nets, anchors, and the like from entangling or otherwise damaging the wellhead.
Like the other prior art, however, the '210 reference does not teach a self-installing system as contemplated in the present invention, as it requires the utilization of dive teams or the like for underwater support and preparation of the installation site.
Thus, based upon the above and foregoing, one can readily ascertain that the searched for invention has not been anticipated in the prior art.